Blood pressure levels and cardiovascular risk according to age in patients with diabetes mellitus: a nationwide population-based cohort study

Background: Little is known about age-specific target blood pressure (BP) in hypertensive patients with diabetes mellitus (DM). The aim of this study was to determine the BP level at the lowest cardiovascular risk of hypertensive patients with DM according to age. Methods: Using the Korean National Health Insurance Service database, we analyzed patients without cardiovascular disease diagnosed with both hypertension and DM from January 2002 to December 2011. Primary end-point was composite cardiovascular events including cardiovascular death, myocardial infarction and stroke. Results: Of 241,148 study patients, 35,396 had cardiovascular events during a median follow-up period of 10 years. At the age of < 70 years, the risk of cardiovascular events was lower in patients with BP < 120/70 mmHg than in those with BP 130–139/80–89 mmHg. At the age of ≥ 70, however, there were no significant differences in the risk of cardiovascular events between patients with BP 130–139/80–89 mmHg and BP < 120/70 mmHg. The risk of cardiovascular events was similar between patients with BP 130–139/80–89 mmHg and BP 120–129/70–79 mmHg, and it was significantly higher in those with BP ≥ 140/90 mmHg than in those with BP 130–139/80–89 mmHg at all ages. Conclusions: In a cohort of hypertensive patients who had DM but no history of cardiovascular disease, lower BP was associated with lower risk of cardiovascular events especially at the age of < 70. However, low BP < 130–139/80–89 mmHg was not associated with decreased cardiovascular risk, it may be better to keep the BP of 130–139/80–89 mmHg at the age of ≥ 70.